Co-owned U.S. Pat. No. 4,195,780 discloses an external flow-amplifying nozzle in which a tapered nozzle section is adjustably mounted upon a body section. The parts are constructed to provide a metering passage which extends radially outwardly between a pair of opposing transverse surfaces provided by the respective parts. The metering passage merges with a forwardly-facing flow-directing passage of annular configuration. Fluid under pressure discharged from the flow-directing passage travels forwardly along the outer surface of the tapered nozzle section. Such primary air, escaping at high velocity from the nozzle, entrains large quantities of secondary air surrounding the nozzle, drawing such secondary air forwardly. The flow from the nozzle is thereby amplified to create a total flow which is substantially greater than the flow of primary air alone.
The commercial version of the nozzle disclosed in U.S. Pat. No. 4,195,780 is widely known and used in industry for cleaning, drying, and convective cooling. Such a nozzle is dimensioned for attachment to conventional air hoses and rigid pressure lines. In a substantial proportion of the nozzle's applications, the adjustability of such a nozzle is a significant advantage.
There are, however, situations in which nozzle adjustability is less important than minimum nozzle size. FIG. 1 depicts in generalized form a type of non-adjustable miniaturized nozzle in current use. An insert 10 has a tubular sleeve portion 11 received in tubing 12. A collar 13 fits over the tubular sleeve of the insert and is secured by solder 14 to tube 12 and sleeve 11. Air under pressure enters the nozzle through tube 12, flows outwardly through radial openings 15 in sleeve portion 11, and then travels forwardly through annular opening 16 and along the tapered outer surface of the nose or tip portion of insert 10, all as represented by the solid arrows in FIG. 1. In one form, the annular opening 16 is actually an annular series of openings separated by circumferentially spaced ribs formed as an integral part of insert 10 and engaging the inner surface of collar 13 to produce a tight frictional fit between the collar and the insert.
A disadvantage of such a construction lies in the risk that insert 10 might become loosened in use and expelled as a high-speed projectile under the force of pressurized air or other fluid, as represented by the dashed lines in FIG. 1. Although the likelihood of such expulsion would be reduced by the exercise of extreme care in establishing that at least some of the solder invades the space between the telescoping surfaces of sleeve portion 11 and tube 12, and by constructing the insert so that a press fit is developed between the outer surface of the insert and the forward end of collar 13, thereby forming the multiplicity of discharge openings described above, a risk still remains, and such risk may become magnified by operating conditions which expose such a nozzle to vibration, impact, elevated temperatures, and general abuse.
Other references illustrative of the state of the art are U.S. Pat. Nos. 3,801,020, 3,795,367, 3,806,039, 3,743,186, and 4,046,492.